The sun’s magnetic field is 10 times stronger than previously believed, finds a study which can potentially change understanding of the processes that happen in the sun’s immediate atmosphere.
The study found that the sun’s corona extends millions of kilometres above the surface, measuring 1,400,000 kilometres across — 109 times larger than Earth — and 150,000,000 km from Earth.
“Everything that happens in the sun’s outer atmosphere is dominated by the magnetic field, but we have very few measurements of its strength and spatial characteristics,” David Kuridze, research student at the Aberystwyth University.
Using the Swedish 1-m Solar Telescope at Roque de los Muchachos Observatory, La Palma, in the Canary Islands, Kuridze studied a particularly strong solar flare which erupted near the surface of the sun on 10 September 2017.
Solar flares appear as bright flashes and occur when magnetic energy that has built up in the solar atmosphere is suddenly released.
“This is the first time we have been able to measure accurately the magnetic field of the coronal loops, the building blocks of the sun’s magnetic corona, which such a level of accuracy,” Kuridze said.
Until now, successful measurement of the magnetic field has been hindered by the weakness of the signal from the sun’s atmosphere that reaches Earth and caries information about the magnetic field, and limitations in the instrumentation available.
The magnetic fields reported in the study are similar to those of a typical fridge magnet and around 100 times weaker than the magnetic field encountered in an MRI scanner.
However, they are still responsible for the confinement of the solar plasma, which make up solar flares, as far as 20,000 km above the sun’s surface.
These solar flares can lead to storms which, if they hit Earth, form the northern lights – the Aurora Borealis.
They can also disrupt communications satellites and GPS systems, the researchers noted.